Android开发ViewPager带红点定时循环

一、效果图

是定时自动切换的，没弄gif，大家懂就行

二、思路

上方用viewpager,下面用LinearLayout动态添加view，view设置setBackgroundResource。然后用RxJava做间隔时间循环操作vp的setCurrentItem,然后vp的onPageSelected来控制LinearLayout里的view那个选中。这样就转起来了

三、案例关键代码

1.view的background

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_selected="true">
        <shape android:shape="oval">
            <solid android:color="@color/c_f44336"/>
        </shape>

    </item>

    <item
        android:state_selected="false">
        <shape android:shape="oval">
            <solid android:color="@color/c_bd"/>
        </shape>

    </item>
</selector>

2.整体代码

        initPoint(fragments.size,llRecommendActivePoints!!)
        if (fragments.size > 1) {
            startLoopRecommend(fragments.size)
        }
        vpRecommendActive?.addOnPageChangeListener(object :ViewPager.OnPageChangeListener{
            override fun onPageScrollStateChanged(p0: Int) {

            }

            override fun onPageScrolled(p0: Int, p1: Float, p2: Int) {

            }

            override fun onPageSelected(pos: Int) {
                var i = 0
                if(llRecommendActivePoints != null){
                    while (i< llRecommendActivePoints!!.childCount){
                        llRecommendActivePoints!!.getChildAt(i).isSelected = false
                        i++
                    }
                }
                llRecommendActivePoints?.getChildAt(pos)?.isSelected = true
            }

        })

其中：

private fun initPoint(pointSize: Int, ll: LinearLayout) {
    ll.visibility = View.VISIBLE
    ll.removeAllViews()
    for (i in 0 until pointSize) {
        //小指标点
        val vPoint = View(context)
        vPoint.setBackgroundResource(R.drawable.active_recommed_point_selector)

        vPoint.isSelected = false
        val params = LinearLayout.LayoutParams(
                UtilHelper.dip2px(context, 8f),
                UtilHelper.dip2px(context, 8f))
        if (i != 0) params.leftMargin = UtilHelper.dip2px(context, 8f)
        vPoint.layoutParams = params

        ll.addView(vPoint)
    }

    if (ll.childCount > 0) {
        ll.getChildAt(0).isSelected = true
    }
}

private fun startLoopRecommend(size:Int){
    if (subscription == null){
        subscription = Observable.interval(4,TimeUnit.SECONDS)
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(Consumer {
                    if (vpRecommendActive != null){
                        var mCurrentItem = vpRecommendActive!!.currentItem
                        if (mCurrentItem == size - 1) {
                            mCurrentItem = 0
                        } else {
                            mCurrentItem++
                        }
                        vpRecommendActive!!.currentItem = mCurrentItem
                    }

                })
    }
}

好了，关键是LinearLayout里面的点生成和控制，喜欢的点个赞